Buttonhole sewing machine which automatically forms barring and covering stitches



Feb. 18, 1969 E.JINDRICH ETAL 3,428,006

BUTTONHOLE SEWING MACHINE WHICH AUTOMATICALLY FORMS EARRING AND COVERING STITCHES Filed Jan. 16, 1967 Sheet of 4 m /5 Q Q 9 l7f-- 13 l ,0 8 0 L. .J L/ L :r

y WW Feb. 18, 1969 E. JlNDi lCH E AL NG EARRING AND COVERING STITCHES 3,428,006 FORMS BUTTONHOLE SEWI MACHINE WHICH AUTOMATICALLY Sheet Filed Jan. 16, 1967 Feb. 18, 1969 E. JINDRICH ET AL 3,428,006

BUTTONHOLE SEWING MACHINE WHICH AUTOMATICALLY FORMS EARRING AND COVERING STITCHES Filed Jan. 16, i967 Sheet 3 of 4 Feb. 18, 1969 MACH EARRING AND E. Jmolcl-l ET Al. BUTTONHOLE SEWING Filed Jan. 16. 1967 3,428,006 INE WHICH AUTOMATICALLY FORMS COVERING STITCHES Sheet 4 of 4 INVENTDRS a h A ZC/vw/ 570050; fkanf/fc United States Patent ABSTRACT OF THE DISCLOSURE A sewing machine for making a seam of zig-zag stitches about the edges of a keyhole-shaped, elongated buttonhole equipped with cams, linkages, and tripping mechanisms which cause the worktable to move transversely of the buttonhole once back and forth after completion of the key hole seam and rotate the sewing implements through 90 during the first stroke of the back-and-forth movement, whereby a row of angularly oifset zig-zag stitches is formed during the first stroke, and a row of covering stitches during the return stroke of the worktable Background of the invention Known automatic sewing machines form a seam of zigzag stitches about a keyhole-shaped buttonhole, the seam having two approximately straight and parallel end portions and an arcuate or bight portion which connects the straight portions. Two-thread chain stitches are commonly preferred for forming the seam.

The seam has two free ends remote from the bight portion which must be finished in some manner for better appearance and for strengthening the narrow end of the buttonhole against tearing of the fabric.

The finishing method which heretofore produced the most satisfactory results required the transfer of the work piece from the buttonhole machine to another sewing machine on which a row of long barring stitches was laid across the free ends of the buttonhole seam proper, and were then overlaid with covering stitches at right angles.

A mechanically adequate finish was also obtained by extending the straight portions of the seam beyond the narrow end of the buttonhole and shifting them toward each other so that they parially overlap. This method can be performed on a single sewing machine, but the appearance of the buttonhole so produced is considered objectionable by many users.

In a third known method, a row of stitches was laid across the ends of the straight portions of the buttonhole seam proper in the manner of the covering stitches referred to above. While the appearance of a buttonhole finished in the last-mentioned method is satisfactory, and the method can be performed on a single sewing machine, the mechanical strength of such a buttonhole leaves much to be desired.

Summary of the invention In order to produce on a single sewing machine a finished buttonhole which combines good appearance with adequate mechanical strength, we provide an otherwise conventional zig-zag buttonhole sewing machine with a system of cam arrangements of which the first responds to the comppletion of the keyhole-shaped buttonhole seam proper for moving the worktable in a direction transverse of the straight portions of the keyhole seam. The sewing implements move from one of the free ends of the keyhole seam toward the other free end of the seam during this movement of the worktable, which is then reversed into 3,428,006 Patented Feb. 18, 1969 the opposite so that the sewing implements move back toward the position originally occupied at the completion of the keyhole seam.

A second cam arrangement turns the sewing implements about an axis perpendicular to the work piece during the first or transverse table movement, and maintains the angular position of the sewing implements during the return movement of the worktable in the opposite direction.

The sewing implements continue operating during the worktable movements and during their turning movement so that a row of zig-zag barring stitches is laid across the free ends of the keyhole seam during the transverse table movement, and each stitch of the row is angularly offset from the preceding stitch. While the first stitch in the row is approximately parallel to the stitches in the free end of the keyhole seam, the last stitch in the row is approximately perpendicular to the original direction. This stitch orientation is then maintained during the table movement in the opposite direction so that a row of covering stitches is laid over the barring stitches.

The resulting finish of the narrow buttonhole end is as strong and as good in its appearance as the afore-described finish produced on two separate sewing machines, yet it can be made fully automatically on a conventional buttonhole sewing machine modified according to this invention to provide the necessary cam arrangements.

Brief description of the drawing The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which:

FIG. 1 shows a buttonhole sewing machine of the intion in side elevation;

FIG. 2 shows the operating elements of the machine of FIG. 1 in a perspective view, many elements being represented in a conventional manner, and others, known in themselves and performing their known functions, being omitted for the sake of clarity;

FIG. 3 is a bottom plan view of a cam which moves the work table transversely of the buttonhole during formation of the key-hole seam;

FIG. 4 illustrates a stopping mechanism of the machine for stopping longitudinal work table movement after completion of the keyhole seam and associated elements in a view corresponding to that of FIG. 2;

FIG. 5 shows the device of FIG. 4 in a diiierent operatmg position;

FIG. 6 shows the cam members and associated elements of the arrangement for moving the worktable and turning the sewing implements during the formation of the barring and covering stitches, the view being in elevational section on the the common axis of rotation of the cam members;

FIG. 7 shows a portion of the device section on the line A-A;

FIG. 8 shows a portion of the device of FIG. 7 in a different operating position;

FIG. 9 is a top plan view of the cams and of selected other elements of the device of FIG. 6;

FIG. 10 diagrammatically illustrates the cycle of operation of the principal elements of the buttonhole sewing machine;

FIG. 11 shows the stitchpattern of a buttonhole of the invention without its covering stitches; and

FIG. 12 shows the narrow end of the buttonhole of FIG. 11 and the pattern of stitches associated therewith.

of FIG. 6 in plan A Description of the preferred embodiment The buttonhole sewing machine of the invention shown in FIG. 1 has a stand 1 which encloses the base portion 2 of the sewing machine mechanism arranged under the machine bed and carries the machine head 3. The head supports the mechanism for operating the needle assembly 4 and an arm 6 which carries the blade 7 for cutting a keyhole into a fabric backed by an anvil 8 in the base 2.

The portion of the mechanism enclosed in the stand 1 includes the actuating device for moving the work support table 9 and other elements necessary in sewing machines for making buttonholes, also the operating mechanism for the gripper or looper (FIG. 2). Fingers 10 are mounted on the table 9 for holding the fabric fast during sewing. The fingers 10 may be operated manually by a lever 11. FIG. 1 also shows the handle 12. of the conventional starting arrangement of the sewing machine, not otherwise shown.

As indicated in FIG. 2 by arrows A-B and P-R, the elongated table 9 is mounted between the base 2 and the head 3 in a generally horizontal position, and a work piece on the table may be reciprocated longitudinally and also moved transversely by pivotal movement of the table about the vertical axis of a shaft 13.

The table 9 is moved longitudinally in the direction of elongation of the buttonhole to be produced by means of the shaft 13 which is journaled in a vertical bore 14 of the table 9, and whose free top end carries a freely rotatable slide 15 received in a longitudinal guide groove 16 of the head 3 (FIG. 1).

The bottom end of the shaft 13 in the base 2 carries a cam follower 17 received in an eccentric annular groove 18 in the top face of a plate cam 19. The cam is rotatably mounted on a vertical shaft 20 and has a worm gear rim which drivingly meshes with a worm 21.

The table 9 is pivoted about the shaft 13 by a stud 22 which engages a longitudinal groove 23 on the underside of the table and is fast on an arm 24 of a bellcrank lever 25, the lever being journaled in bearings 26, 27 of the base 2. The free end of the arm 24 carries a cam follower 28 which is slidably received in a groove 29 on the underside of a plate cam 30 better seen in FIG. 3. The walls of the groove 29 have projections 31, 32 and one wall is formed with an opening 33 associated with a recess in the other wall.

The stand 1 also encloses an electric motor, not shown, from which power is transmitted by a belt 34 (FIG. 2) to a pulley 35 on a horizontal drive shaft 36 Which is approximately perpendicular to the normal direction of elongation of the table 9. The shaft 36 is journaled in bearings37, 38 and carries the afore-mentioned worm 21. A jaw coupling 39, not shown in detail, permits the shaft 36 to be disengaged from the pulley 35.

Another worm 40, fast on the shaft 36, engages a worm gear 41 on a vertical shaft 42 which is journaled in bearings 43, 44 and whose top end carries the plate cam 30. The bottom end of the shaft 42 carries a cam 46, the function of which will presently become apparent. An auxiliary drive mechanism is mounted on the drive shaft 36 and its function will be described further hereinbelow.

Another belt 47 connects the non-illustrated motor with a pulley 48 which is mounted on a horizontal, transverse drive shaft 49 journaled in the head 3 by bearings 50, 51. A roller clutch 52, not shown in detail, disengageably connects the pulley 48 with the shaft 49.

A projecting control arm 53 of the clutch 52 may be engaged by an arm 54 of a three-armed lever 55 to release the shaft 49 from the pulley 48. The lever 55 is pivotally attached to the head 3 by a pin 57, and is biased in a counter-clockwise direction by a helical tension spring 58 attached to the second arm 56 of the lever 55 and by a hook-shaped end portion 59, to a pin 60 on the head 3. The free end of the third lever arm 61 cammingly cooperates with an abutment 62 on the table 9 during the longitudinal movement of the table. A horizontal pin 63 on the abutment 62. pivotally supports a detent 64 whose clockwise movement under the force of gravity is limited by a stop 65.

The lever 55 is held in the fully drawn position against the force of the spring 58 by an offset 69 on one arm of a lever 66 which is mounted on a fulcrum 67 on the head 3. A spring 68 biases the lever 66 toward the position shown in full lines. The lever 66 is connected by a pivot 70 to a pull rod 71 which will be referred to hereinafter.

The drive shaft 49 carries an eccentric 72 which is received in the forked arm 73 of a lever 74 secured to the arm 3 by a pivot 75. A link 77 is connected by hinges 76, 78 to the lever 74 and to another link 79 which is pivotally attached to the operating arm 81 of the mechanism 45 by a pin 80. The drive mechanism 45 is a unidirectional roller clutch whose driven portion is attached to the arm 81, and whose driving portion is fast on the shaft 36.

A pivot pin 82 fast on the link 77 rotatably supports a slide 83 which is guided in a fork 84 attached to a shifting lever having two arms 85, 87 and is fulcrumed at 86 on the base 2. When the lever 74 is pivoted by the eccentric 72, the arm 81 is swung about the axis of the shaft 36. The shaft 36 is thus turned by the clutch 45 by one step during each revolution of the shaft 49 for stepwise longitudinal movement of the table 9 by the cam 19. The table is also rocked intermittently about the axis of the shaft 13 by the worm 40, worm gear 41, shaft 42, plate cam 30, and lever arm 24 while the clutch 39 is disengaged and the shaft 49 is driven.

The clutch 39 is controlled in a known manner, not shown, but analogous to the control of the clutch 52, by the arm 61 of the lever 55, the arrangement being such that the clutch 39 is engaged and the clutch 52 is disengaged when the lever 55 is in the position indicated in FIG. 2 in broken lines. The intermittent longitudinal and rocking movements of the table 9 continue While the buttonhole edges are being sewn, as will become apparent from the description of FIG. 10.

The free end of the shaft '49 remote from the pulley 48 carries a bevel gear 88 meshing with a bevel gear 89 on the shaft 20 which is journaled in bearings 90, 91 in the head 3 and the base 2 respectively. A bevel gear 92 near the lower end of the shaft 20 meshes with a bevel gear 94 on a horizontal shaft 95 which causes swinging movement of the gripper mechanism 5 in a known manner. The bottom end of the shaft 20 carries an eccentric 93.

The reciprocating vertical movement of the needle assembly 4 and the swinging movement thereof are also derived from the drive shaft 49 in a manner not shown in the drawing, but conventional in zig-zag sewing machines, and described in more detail in our simultaneously filed application, Ser. No. 609,552.

The rotary movement of the needle mechanism 4 and of the gripper mechanism 5 about a vertical axis, which are necessary for stitching around the 'bight portion of the button hole are controlled by the plate cam 19. A groove on the underside of the plate cam .19, not visible in the drawings, but more fully shown in the aforementioned copending application, receives a cam follower 96 rotatably mounted by a pin 97 on a rocker 98 which is pivoted on a pin 99 in a bearing 100 of the base 2. Hinges 101, 103 and a link 102 connect the rocker 98 to an arm 104 on a vertical shaft 105 which is supported in the head 3 and the base 2 in bearings 106, 107 and carriers gear segments 108, 109 respectively meshing with gears 110, 111 of the needle and gripper mechanisms 4, 5 for rotating the same.

With the exception of the cam 46, detent 64, pivot 70, pull rod 71, and eccentric 93, the structure described so far is substantially known. It is capable of sewing button holes in a piece of textile material held on the table 9 by the fingers 10, the stitch forming apparatus essentially consists of the needle mechanism 4 and the gripper mechanism 5. The invention is more specifically concerned with the elements to be described hereafter,

which permit barring stitches and covering stitches to be formed in a pattern characteristic of this invention.

A tension spring 112 tends to pivot the lever arm 87 in the direction of the arrow F into abutting engagement with an offset 114 on an arm 115 whichis attached to the base 2 by a pivot 116. The free end of the arm 115 extends into the path of the detent 64 on the work table 9. A tension spring 117 biases the arm 115 in the direction of the arrow K toward the illustrated position. When the detent 64 engages the arm 115 while the table 9 moves in the direction of the arrow B, the arm 1'15 releases the lever arm 87 by moving in the direction of the arrow L, and the spring 112 pivots the arm 87 until it abuts against a stop 120 on a rocker 118.

The fork 84 and the attached lever 85, 87 thereby move to the position illustrated in FIG. 4, and the detent 64 clears the arm 115. When the leading edge of the worktable 9 approaches its terminal position in the direction of the arrow B, it engages the free end of the rocker 118 and pivots the rocker on its fulcrum 119 into the position shown in FIG. 5, whereby the lever 87 is returned to its original position and engages the offset 114 of the arm 115 under the tension of the spring 117.

As is evident from joint consideration of FIGS. 4 and 5, the movement of the link "77 caused by the hinge 76 after the afore-described engagement of the arm 11-5 and the rocker 118 by the detent 6'4 and the table ed-ge no longer results in motion of the arm 81 of the drive mechanism 45, whereby the stepwise longitudinal movement of the table 9 is interrupted while the operation of the stitch-forming elements continues. This permits barring stitches to be formed at the end of the buttonhole.

As illustrated in more detail in FIGS. 6' to 9, a plate cam 121 is rotatably mounted on a vertical pin 122 fastened on the base 2. The cam is operated by the aforementioned eccentric 93 which is enveloped by follower ring 123 on a connecting rod 124 fastened to the plate ca-m assembly by a bolt 125, as is best seen in FIG. 6.

The bolt 125 is radially adjustably fastened in a groove 126 of a disc 127 which is attached to the approximately triangular, driven, central member 128 of a roller clutch by screws 1'29. Rollers 130 are interposed between the member 128 and a peripheral sleeve 132 of the clutch, and are biased toward a position of simultaneous engagement with the sleeve 132 and the driven member 128 by compression springs 131. The disc 127 and the driven clutch member 128 are rotatably mounted on the pin 122 and are axially secured in abutting engagement with a shoulder 133 on the pin by a washer 134, a spring washer 135, and a screw 136.

The sleeve 132 has an integral flange which is connected with a drive ring 138 by axial pins 137. The inner circumference of the ring r138 has notches 139 of approximately semi-cylindrical section about axes which are parallel to the axis of the pin 1-22. The ring 138 is rotatably arranged in an annular recess 140 of the plate cam 121.

The plate cam has a single circular opening 141 in which a coupling pin 142 is rotatably mounted. An axial end portion of the pin 142 is cylindrical and carries a lug 143 which projects outwardly from the cam 121 as seen in FIG. 9. The central portion 144 of the pin 142 is of semi-cylindrical section and couples the plate cam 121 to the ring 138 when swung into the position shown in FIG. 8. A compression spring 145 engages the lug 143 and biases the pin 142 toward the coupling position.

The lug 143 is normally held in a position in which the central pin portion 144 is flush with the body of the plate earn 121, as shown in FIG. 7, by an upright arm of a rocker 146 pivoted on a horizontal pin 147 in the base 2, and biased by a weak tension spring 113 into abutment of its approximately horizontal arm against a stationary stop 167. The horizontal rocker arm is also within range of the free end 148 of the lever arm 85.

The upper face of the plate cam 121 has an annular cam track or groove 149, best seen in FIG. 9, which has an enlarged portion 150. A radial cam 151 is fixedly fastened on the plate cam 121 near the center of its upper face. The periphery of the plate cam 121 carries an axially projecting cam lobe 152 and a pin 153. The radial cam 151 cooperates with a cam follower 154 on the arm 155 of the rocker 98, whereby rotary movement of the needle mechanism 4 and the gripper mechanism 5 may be actuated.

Pivotal movement of the worktable 9 in the direction of the arrows P, R may be caused 'by a cam follower pin 156 on an arm 157 of the bellcrank lever 25 which engages the groove 149 of the plate cam 121. While the cam follower pin 156 is located in the enlarged portion 150 of the cam groove 149, and the cam follower 28 en gages the opening 33 in the groove 29 of the plate cam 30, the worktable 9 is secured against pivoting movement by a locking lever 158 which is rotatably mounted on a pivot pin 159 in the base 2. The terminal portion 160 of one of the arms of the lever 158 is hook-shaped and adapted to engage the pin 156. The other arm of the locking lever 158 carries a cam follower 161 which is biased by a spring 162 against the radial cam 46 on the bottom end of the shaft 42.

The sewing operation is stopped when the cam lobe 152 on the plate 121 engages a cam follower 163 on a rocker 164 which is pivoted to the base 2 by a pin 165. The other end of the rocker 164 is connected with the pull rod 71 by a hinge 166. When the rocker is pivoted in the direction of the arrow Z, the lever 55 is released by the lever 66, and disengages the clutch 52.

The operation of the afore-described sewing machine will now be explained with reference to FIG. 10. In this timing diagram, the row 1 shows rotary movement of the plate cam 19 by hatching, wherein cross-hatching indicates relatively fast movement and simple hatching relatively slow movement. Rows 2A and 2B indicate in a corresponding manner motions of the work table 9 in the direction of the arrows A and B respectively. Rows 3P and 3R show the pivotal movement of the table 9 in the directions of the arrows P and R respectively. Hatching in rows 4X and 4Y shows the rotary movements of the needle mechanism 4 and of the gripper mechanism 5 in the directions of arrows X and Y respectively (FIG. 2). Row 5 is hatched where the plate cam 121 is rotated. Where row 6 is hatched, the needle mechanism 4 and the gripper mechanism 5 per-form their convention-a1 stitch forming movements. Row 7 indicates the table locking engagement of the hook 160 on the locking lever 158 with the cam follower pin 156. The short operative period shown in row 8 cor-responds to the piercing of the buttonhole by the blade 7. V

The successive operating periods w to W are represented by columns of the diagram. Column W indicates the initial or rest period of the sewing machine, wherein the pulleys 35 and 48 are rotated idly on the associated shafts 36, 49 by the non-illustrated motor. During the period W all preliminary movements and operations are performed from the starting of the sewing machine to the beginning of buttonhole sewing. W is the period during which one straight side of the buttonhole is being sewn. During period W the arcuate or bight portion of the hole is being sewn, and the other straight side of the buttonhole is sewn during the period W Barring stitches and cover stitches at the narrow end of the buttonhole are formed during period W and the machine reverts to its starting position during period W Roman numerals associated with the time axis of the diagram have the following meanings:

The machine is started at I by means of the lever 12. Sewing is started at II by the pivotal movement of the three-armed lever 55 which controls the clutch 52. Sewing around the arcuate edge portion of the buttonhole starts at III, and the sewing implements reach the transverse plane of symmetry of the buttonhole at IV. Sewing of the arcuate edge is completed at V, and the sewing implements reach the narrow end of the buttonhole remote from the arcuate portion at VI, whereupon formation of the barring stitches and cover stitches starts. The pivotal movement of the worktable 9 in the direction of the arrow P is stopped at time VII, and the formation of barring stitches is thereby terminated. Cover stitches are formed during the pivotal movement of the worktable in the direction of the arrow R. Transverse movement of the work table 9 ends at VIII, and the sewing operation is stopped by disengagement of the roller clutch 52 by the threearmed lever 55. The working cycle of the machine is completed at IX with the return of the mechanism to its starting position.

Arrows extending from one row to the other indicate the manner in which the several operating elements of the sewing machine influence each other.

FIG. 11 diagrammatically illustrates the stitch pattern formed about the circumference of a buttonhole by the sewing mechanism, with the exception of the covering stitches, and Roman numerals IIVII indicate the positions of the sewing implements in the corresponding periods shown in FIG. 10. FIG. 12 shows in more detail the stitch pattern near the narrow end of the buttonhole in a manner corresponding ot FIG. 11, but on a larger scale, and including the cover stitches.

In the starting position of the apparatus, the worktable 9 is in the terminal position indicated in FIG. by a showing of the leading table edge in broken lines, and in which the worktable 9 engages the rocker 118. The plate cam 19 simultaneously is in a position in which the cam follower 17 is located in the mid-point of a portion of the groove 18 which is circular about the axis cam rotation.

After a workpiece in which a buttonhole is to be sewn has been clamped between the worktable 9 and the fingers 10, operation of the sewing machine is started by depressing the lever 12. The lever is connected with the jaw coupling 39 in a manner not further illustrated so that rotation of the shaft 36 by the pulley 35 is started. The worms 21, 40 start rotating the plate cams 19 and 30.

The arm 6 which supports the cutting blade 7 is actuated next by the plate cam 19 in a manner not further illustrated since it is conventional in itself, whereby a keyhole is cut in the workpiece while the table 9 stands still, the cam follower 17 traveling in the afore-mentioned circular portion of the groove 18. When the cam follower 17 reaches a part of the groove 18 whose center of curvature is not in the cam axis, the work table 9 moves from the afore-described terminal position in the direction of the arrow A. The obliquely inclined underside of the detent 64 moves over the free end of the arm 115 and is thereby pivoted counterclockwise, as viewed in FIG. 2, on the pin 63 until it clears the arm 115, and is thereafter returned to the illustrated angular position by gravity.

The abutment 62 on the worktable 9 engages the end portion 61 of the lever 55 and pivots the lever on the pin 57 from the position shown in broken lines in FIG. 2 clockwise toward the posiiton shown in fully drawn lines against the restraint of the spring 58, whereby the arm 54 of the lever permits the clutch 52 to rotate the drive shaft 49. The jaw coupling 39 is simultaneously disengaged by a non-illustrated linkage with the lever arm 61, so that rotation of the shaft 36 is stopped, and continuous movement of the work table 9 in the direction A is terminated.

When the shaft 49 rotates, the needle mechanism 4 and the gripper mechanism 5 are operated. The gripper mechanism is actuated by means of the bevel gears 88, 89. All conventional movements of the gripper mechanism are derived in a manner not further illustrated from the rotation of the horizontal shaft 95 with the exception of the rotation in the direction of the arrows X, Y. The normal sewing movements of the needle mechanism 4 are similarly derived from the rotation of the drive shaft 49 by means of a similar linkage conventional in itself and not further illustrated, but partly described in our afore-mentioned application. The non-illustrated linkage causes not only the vertical reciprocating movement of the needle bar, but also the pendulum movement necessary for zig-zag stitching.

Operation of the mechanisms 4, 5 causes stitches to be formed first along one of the straight sides of the buttonhole, that is, from position 11 to position III in FIG. 11 which requires intermittent movement of the table 9 in the direction of the arrow A. This movement is caused by the eccentric 72 which is permanently connected with the horizontal drive shaft 49 and engages the fork 73 of the lever 74.

The swinging movements of the hinge 76 in the directions of the arrows G, H are converted into movements of the lower end of the link 77 about the pivot pin 82 in the directions of the arrows C, D, and this movement is transmitted to the arm 81 of the roller clutch 45. The resulting intermittent operation of the worm 21 causes the necessary stepwise advance of the worktable 9. The lever carrying the fork 84 is secured during sewing in the position illustrated in FIG. 2 by engagement of its arm 87 with the offset 114 on the arm under the tension of the spring 112.

When the sewing implements reach the position III in FIG. 11, and sewing of one straight side of the buttonhole is terminated, the worktable 9 starts its pivoting movement in the direction of the arrows P, R while continuing longitudinal movement to permit sewing of the arcuate seam along the edge of the enlarged end portion of the keyhole. The pivoting movement of the table 9 is intermittently derived from the horizontal shaft 36 by means of the worm 40, worm gear 41, and shaft 42 which cause rotation of the plate cam 30. When the cam follower 28 engages the projections 31, 32 in the groove 29, the bellcrank lever 25 is turned in the bearings 26, 27, and the stud 22 pivots the worktable about the shaft 13 in the directions of the arrows P, R.

Simultaneously, the needle mechanism 4 and the gripper mechanism 5 are turned about their vertical axis by the cam follower 96 which engages the groove, not seen in the drawing, on the underside of the plate cam 19 and causes angular movement of the rocker 98 transmitted to the arm 104 on the shaft 105, whereby the gears 110, 111 of the mechanisms 4, 5 are rotated by the segments 108, 169.

When the sewing implements complete sewing of one half of the seam along the arcuate edge of the buttonhole and reach the position IV, the cam follower 17 is in the most eccentric portion of the groove '18, and starts moving the worktable 9 back toward the starting position indicated in FIG. 5 in the direction of the arrow B. The manner in which the sewing implements move about the outline of the buttonhole, as described above, is essentially conventional.

It is necessary in the sewing machine of the invention that the cam follower pin 156 on the arm 157 of the bellcrank lever 25 be released from the hook-shaped end 160 of the locking lever 158 to permit simultaneous longitudinal and transverse movement of the worktable 9 while stitches are sewn around the keyhole. Release of the cam follower pin 156 is controlled by the cam 46 on the shaft 42. The throw of the eccentric cam 46 is sufficient, and its angular position is such that the locking lever 158 is swung against the tension of the spring 162 while the sewing implements travel between positions III and V until the pin 156 is released from the hook 160. During the rotary movement of the bellcrank lever 25 caused by engagement with the projections 31, 32 in the groove 29 of the plate cam 30, the pin 156 moves in the enlarged portion 150 of the cam groove 149 in the plate cam 121.

When the sewing implements reach the position V, the cam follower 28 engages a circular portion of the groove 29 in the plate cam 30 so that the transverse movement of the worktable 9 in the direction of the arrows P, R is stopped when the worktable is in the central position. The worktable 9 is then secured against further transverse movement by the locking lever 158. The cam 46 moves away from the cam follower 161 of the locking lever 158 until the hook-shaped end '160 again engages the cam follower pin 156, and the condition illustrated in FIG. 2 is restorted.

The worktable 9 moves in a straight line while the sewing implements move from piston V to position VI. This portion of the operation of the sewing machine thus is essentially conventional. The arm 115, rocker 118, and lever 85, 87 assume the position shown in FIG. 2 during the rectilinear travel of the worktable 9.

As is best seen in FIG. 5, the direction of movement of the slide 83 in the fork 84 is angularly offset from the direction of movement of the link 77 as the lever 74 is pivoted by the eccentric 72. While the eccentric rotates, the clutch 45 is oscillated by the displacement of the link 77 between the positions respectively indicated in fully drawn and broken lines in FIG. 5, whereby the shaft 36 is turned intermittently.

When the arm 115 is swung in the direction of the arrow L by the detent 64 as the table 9 approaches the terminal position of its straight movement, the tension spring 112 positions the lever arm 87 against the stop 120 as shown in FIG. 4 so that the slide 83 moves in the direction of elongation of the link 77 during the rotation of the eccentric 72 which has no further influence on the clutch 45. The arm 81 remains stationary as shown in FIG. 4, and the longitudinal movement of the table 9 is stopped.

The free end 148 of the lever arm 85 simultaneously releases the horizontal arm of the rocker 146, and the rocker is pivoted counter-clockwise, as viewed in FIG. 4, by the compression spring 145 which acts on the lug 143 of the coupling pin 142 and overcomes the restraint of the weaker tension spring 113. The lug 143 is turned into the position indicated in broken lines in FIG. 9, whereby the coupling pin 142 assumes the position illus trated in FIG. 8 and connects the cam 121 with the connecting rod 124. The rotary movement of the shaft 20 is intermittently transmitted to the cam 121 which turns stepwise on the pin 122. The lug 143 clears the vertical arm of the rocker 146, and the rocker then is returned by the tension spring 113 to the position shown in FIGS. 2 and 5.

The plate cam 121 is turned by its roller clutch in the direction of the arrows in FIGS. 7 and 8, and the cam follower pin 156 moves with the cam 121 until it engages the hook-shaped end 160 of the locking lever 158. The pin then travels in the groove 149 relative to the cam 121. The work table 9 is thereby moved stepwise in the direction of the arrows P, R, the bellcrank lever 24 being pivoted by the plate cam 121 and the cam follower pin 156. Since the sewing movement of the mechanisms 4, continues, there are formed barring stitches on the workpiece while the sewing implements travel from VI to VII.

Because of the engagement of the radial cam 151 on the plate cam 121 with the cam follower 154 on the rocker 98, the needle mechanism 4 and the gripper mechanism 5 are simultaneously turned. The resulting stitch pattern is shown in FIG. 12 in which the barring stitches are sequentially numbered 1 to 8'. They are also shown in FIG. 11 from which the cover stitches have been omitted for the sake of greater clarity. The mechanisms 4, 5 are rotated through an angle of 90, and it is immaterial for the success of the operation whether the rotas tion is in the direction of the arrow X or of the arrow Y although it will be appreciated that the pattern produced is affected by the direction of the rotation.

The transverse movement of the worktable 9 during movement of the sewing implements from position VI to position VII and formation of the baring stitches is selected so that it extends over the full width of the stitches along both straight portions of the buttonhole as is evident from FIG. 12.

When the position VII is reached, the transverse movement of the worktable 9 is reversed by the plate cam 121. The cam follower 28 is located in the opening 33 of the groove 29 in the plate cam 30 while the barring stitches are formed, and the cam follower 96 is simultaneously located in a corresponding recess of the non-illustrated groove on the underside of the plate 19 which is generally similar to the groove 29 shown in the top face of the plate cam 30 (FIG. 3), but is more fully illustrated in our copending application. During the return transverse movement of the worktable 9, the sewing implements move from the position VII to the position VIII without further turning and form a series of covering stitches which secure the previously formed barring stitches.

When the position VIII is reached, the cam lobe 152 on the plate cam 121 engages the cam follower 163 of the rocker 164, and pivots the latter on the pin 165 clockwise, as indicated by the arrow Z in FIG. 2, whereby the lever 66 is swung on its fulcrum 67 from the position shown in fully drawn lines to the position indicated by broken lines in FIG. 2, the lever 55 is: released from the offset 69 and is swung by the tension spring 58 into engagement with the operating arm 53 of the roller clutch 52 to disengage the clutch.

The pulley 48 freely rotates on the shaft 49 whose movement is thereby stopped. The mechanisms 4 and 5 stop and the clutch 39 again connects the shaft 36 to the non-illustrated motor, whereby the table 9 is moved in the direction of the arrow B into the terminal position in which it is ready to start a new cycle of operation.

Immediately before reaching the terminal position, the table 9 engages and pivots the rocker 118, whereby the lever arm 87 is lifted by the stop 120 from the position shown in FIG. 4 to that illustrated in FIG. 5, and the arm 115 resumes its original position under the tension of the springs 112 and 117. Engagement of the end 148 of the lever arm with the rocker 146 simultaneously returns the coupling pin 142 to its original position against the pressure of the spring 145. The connection between the ring 138 and the plate cam 121 is thereby interrupted, and the mechanism of the invention which forms the barring and covering stitches, as described above, has thus returned to its starting condition. The sewing machine may now be stopped by a non-illustrated limit switch in a known manner if so desired. It is ready to perform another cycle of operations as described hereinbefore.

It should be understood, of course, that the foregoing disclosure relates only to a preferred embodiment of the invention, and that it is intended to cover all changes and modifications of the example of the invention chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. In a buttonhole sewing machine having a worktable movable in two directions intersecting each other and parallel to a supporting surface of the table, holding means for holding a workpiece on said surface, sewing implements for forming zig-zag stitches in the workpiece, and drive means for moving said table in said directions and for operating said sewing implements, said drive means being effective to move the worktable relative to the sewing implements and to turn the sewing implements about an axis transverse to said surface for changing the direction of said zig-zag stitches, to produce a keyholeshaped seam having two substantially straight and substantially parallel portions connected by an arcuate portion and having two free ends remote from said arcuate portion, the improvement comprising:

(a) first cam means operatively connected to said drive means and responsive to completion of said keyholeshaped seam for moving said table in a direction transverse to said straight portions, and for thereby moving said sewing implements relative to said workpiece from one of said free ends toward the other free end, and for thereafter moving said table in a direction opposite to said transverse direction; and

(b) second cam means operatively connected to said drive means for gradually turning said sewing implements about said axis during the moving of said worktable by said first cam means in said transverse direction with each successive zig-zag stitch formed during said turning movement of said sewing implements being angularly offset with respect to each preceding stitch and for maintaining the angular position of said sewing implements relative to said axis during said moving of the worktable by said first cam means in said opposite direction,

(1) the zig-zag stitches formed while maintaining the angular position of said sewing implements being substantially parallel to each other and transverse to the direction of said movements of the worktable,

(2) said drive means including motion transmitting means operating said sewing implement during said movements of the worktable in said transverse and opposite directions.

2. In a machine as set forth in claim 1, said second cam means including means for turning said sewing implements through an angle of substantially 90 while said sewing implements move from a position of longitudinal alignment with one of said straight portions to a position of alignment with the other straight portion.

3. In a machine as set forth in claim 1, said improvement including stopping means for stopping movement of said worktable in the direction of said straight portions while said sewing implements continue being operated by said drive means and while said worktable is moved in said transverse and opposite directions by said first cam means.

4. In a machine as set forth in claim 3, said stopping means including an elongated link member (77) having a plurality of longitudinal portions, actuating means (74) for moving a first one of said longitudinal portions in a predetermined first path, guide means (83, 84) for guiding a second longitudinal portion of said link member in a second path during said movement of the first portion, shifting means (85, 87) for shifting said guide means between a first position in which said paths are substantially aligned (FIG. 4) and a second position in which said paths are angularly offset relative to each other, and motion transimtting means (79, 45, 36, 19, 17, 13, 14) interposed between a third portion of said link member and said worktable (9) and responsive to the movement of said link member in said second position of said guide means for moving said worktable in the direction of said straight portions of said buttonhole seam in response to said movement of said first longitudinal portion, and non-responsive to the movement of said link member in said first position of said guide means.

5. In a machine as set forth in claim 4, said stopping means further including yieldably resilient means (112) urging said guide means to move from said second to said first position, means (115) for normally holding said guide means in said second position against the urging of said resilient means, and engaging means (64) on said worktable for releasing said guide means from said holding means when said worktable reaches a position corresponding to said completion of said seam.

6. In a machine as set forth in claim 1, said first cam means including a cam member (121), a drive member (138) drivingly connected to said drive means, coupling means (142) movable toward and away from an operative position in which said coupling means connect said cam member to said drive member for joint movement, resilient means (145) urging said coupling means toward said operative position, releasable means (146) holding said coupling means away from said operative position, and releasing mean (85, 87, responsive to movement of said worktable (9) into a position corresponding to said completion of said seam for releasing said coupling means from said releasable means.

7. In a machine as set forth in claim 1, said first cam means including a cam member (121) having an axis and defining a cam track (149) about said axis, a cam follower member (156) engaging said cam track, and means (93, 124) for rotating said cam member about said axis while said sewing implements (4, 5) are operated, said improvement further comprising a locking member (158) movable toward and away from a position of locking engagement with said cam follower member, and moving means (36, 46, 161) for moving said locking member toward and away from said locking position in timed sequence with the movement of said worktable in the direction of said straight portions.

8. In a machine as set forth in claim 1, said first cam means including a first cam member (121) having an axis, means (93, 124) for rotating said cam member about said axis while said sewing implements (4, 5) are being operated, and first cam follower means (156, 25, 22) interposed between said cam member and said work table for moving said table in said transverse and opposite directions in response to rotation of said cam member, said second cam means including a second cam member (151) connected to said first cam member for joint rotation, and second cam follower means (154, 98, 105, 108, 111) interposed between said second cam member and said sewing implements for rotating the same in response to the joint rotation of said cam members.

9. In a machine as set forth in claim 1, said first cam means including a cam member (121) having an axis, and means (93, 124) for rotating said cam member about said axis while said sewing implements (4, 5) are being operated by said drive means (47), and linkage means (164, 66, 55, 52) engaging said cam member and operatively connected to said drive means for disconnecting said sewing implements from said drive means in response to a predetermined angular position of said cam member relative to said axis.

References Cited UNITED STATES PATENTS Re. 14,529 10/1918 Allen 11271 240,546 4/1881 Reece 11271 498,216 5/1893 Reece 11271 694,150 2/1902 Hogan 112-73 1,565,241 12/1925 Allen 11271 H. HAMPTON HUNTER, Primary Examiner.

US. Cl. X.R. 

